Enabling a vehicle to follow closely behind one vehicle safely through partial or full automation has significant fuel savings and/or safety or labor savings benefits, but is generally unsafe when a driver tries to do this manually. Presently, during normal driving, vehicle motion is controlled either manually, by a driver or by convenience systems, such as cruise control or adaptive cruise control. The various types of cruise control systems control vehicle speed to make driving more pleasurable or relaxing, by partially automating the driving task. Some of these systems use range sensors and/or vehicle sensors to control the speed to maintain a constant headway relative to the leading vehicle. In general, these cruise control systems provide minimal added safety, and do not have full control of the vehicle (in terms of being able to fully brake or accelerate).
During rare emergencies, the acceleration and braking of a vehicle may be controlled by active safety systems. Some safety systems try to actively prevent accidents, by braking the vehicle automatically (without driver input), or assisting the driver in braking the vehicle, to avoid a collision. These systems generally add zero convenience, and are only used in emergency situations, but they are able to fully control the vehicle's motion.
Driver control does not match the safety performance of even current systems, for several reasons. First, a driver cannot safely maintain a close following distance. In fact, the relatively short distances between vehicles necessary to get any measurable fuel savings results in an unsafe condition if the vehicle is under driver control, thereby risking a costly and destructive accident. Further, the driver is not as capable of maintaining a constant headway as an automated system is. In fact, a driver trying to maintain a constant headway often causes rapid and large changes in command (accelerator pedal position for example), resulting in a loss of efficiency.
It would be desirable to have reliable and economical semi-automated vehicular convoying or platooning systems which enable vehicles to follow closely together in a safe, efficient, convenient manner.
Careful selection of vehicle routing is important to successful vehicle platooning. While various mapping algorithms exist to describe highways and other roads, these algorithms have not led to routing appropriate for vehicle platooning. As a result, there also has arisen a need to develop methods and systems for identifying appropriate sections of roadway over which platooning of vehicles, including tractor-trailer rigs, can be safely conducted.
Further, in some instances it is desirable, and even necessary, to select correctly one specific vehicle out of a plurality of similar vehicles in appearance to sensors or other system capabilities. Still further, it is sometimes important for a first vehicle to identify characteristics of at least a second vehicle while both (or all) vehicles are proceeding at speed on an open road, for example, the length of all or some portion of the second vehicle.
Once the vehicles are selected, initiation of the platoon, or pull-in, requires careful adjustment by the system of the speed of the two vehicles to increase safety margin to compensate for approach speed. In one aspect, the approach speed of the back vehicle relative to the front vehicle is adjusted as a function of the current gap between the vehicles.
In addition to managing the pull-in process for beginning a platoon, the system identifies conditions suggesting or requiring dissolution of the platoon, as well managing the dissolve process.